Search Bar and refresh control on mobile app

I am building an iOS app that helps the user find sports ads. I am using a search bar for the search over a grid (collection view) that displays the ads. I also have a refresh control that is displayed on pulling the grid downwards. I believe the refresh control should be displayed below the search bar and over the grid, and not as a header of the grid, although this could be an alternative.

What do you think is the best approach?